This invention relates generally to inflators for use in inflating inflatable restraint airbag cushions, such as used to provide impact protection to occupants of motor vehicles. More particularly, the invention relates to adapters for joining pyrotechnic initiator devices to or in inflator assemblies.
It is well known to protect a vehicle occupant using a cushion or bag, e.g., an “airbag cushion,” that is inflated or expanded with gas such as when the vehicle encounters a sudden deceleration, such as in the event of a collision. In such systems, the airbag cushion is normally housed in an uninflated and folded condition to minimize space requirements. Upon actuation of the system, the cushion begins to be inflated in a matter of no more than a few milliseconds with gas produced or supplied by a device commonly referred to as an “inflator.”
Various types of inflator devices have been disclosed in the art for the inflation of an airbag such as used in inflatable restraint systems. One type of known inflator device derives inflation gas from a combustible pyrotechnic gas generating material which, upon ignition, generates a quantity of gas sufficient to inflate the airbag.
In view of possibly varying operating conditions and, in turn, possibly varying desired performance characteristics, there is a need and a desire to provide what has been termed an “adaptive” inflator device and a corresponding inflatable restraint system. With an adaptive inflator device, output parameters such as one or more of the quantity, supply, and rate of supply of inflation gas, for example, can be selectively and appropriately varied dependent on selected operating conditions such as ambient temperature, occupant presence, seat belt usage and rate of deceleration of the motor vehicle, for example.
Such adaptive systems typically require the inclusion of additional components as a part of the associated inflator device. For example, various proposed or currently available dual stage inflator devices incorporate two individual initiators for activating gas generation from more than one generally isolated supply of gas generate material. As will be appreciated by one skilled in the art, the incorporation of two initiators can present difficulties in engineering and design.
More specifically, and for example, driver side airbag inflator devices commonly have the general form of a flattened, disk-shaped circular cylinder typically or generally having a length (sometimes referred to as “height”) to diameter ratio of about 0.5 or less. For example, a typical driver side inflator might be about 40 mm in length or height and about 80 mm in diameter. An inflator device having such shape and size provides a familiar and convenient package for insertion in a corresponding or associated airbag module housing. Such disk-shaped inflator devices are often formed of two structural components, i.e., a lower shell or base and an upper shell or cap, that may be desirable and appropriately joined together.
FIGS. 1 and 2 illustrate two configurations of stamped lower shell components that are known and available in the art for inflator devices. The lower shell components shown in FIGS. 1 and 2 each include openings in a base portion adapted to receive initiators therethrough. The lower shell component 10 of FIG. 1 has a double hub stamping configuration including a first hub 12 with an opening 14 for receiving a first initiator (not shown) and a second hub 16 with an opening 18 for receiving a second initiator (not shown). The lower shell component 20 of FIG. 2 has a single hub stamping configuration, wherein a single hub 22 has two openings 24 for receiving both initiators (not shown). The stamped hubs are typically desired, at least in part, to create a “socket” for containing or surrounding the initiator pins into which an electrical connector, connected at the other end to sensors such as, for example, for detecting a collision or rollover, is inserted and secured.
Forming inflator device components, more particularly lower shell components, with relatively complex stamped configurations, such as shown, for example, in FIGS. 1 and 2, generally requires additional, and thus generally more costly, engineering and/or design considerations. A more complex stamping may result in a thinning of the stamped wall, and thus a potential weakening, in portions of the stamped components, such that the stamped inflator base will not satisfy hydroburst requirements. Hydroburst generally refers to a structural integrity test whereby a sealed inflator device housing is internally pressurized, such as, for example, to a pressure typically greater than about 7,000 pounds per square inch, to determine if the inflator device housing will leak or otherwise rupture. Generally, a more complex stamping will result in an undesirable increase in bowing or bending in areas of the lower shell, which can undesirably result in leaks or rupturing of the inflator device housing. To provide an inflator device that can meet hydroburst requirements, increased focus and cost has been directed to the materials used in forming the stamped component as well as the size, configuration and wall thickness of the stamped components.
There is a need for a simplified inflator device stamped lower shell configuration. There is a need for a lower shell configuration providing desired strength with a generally less complex, and thus generally less expensive to form, stamped configuration or “stamping.”